(+)- and (−)-liriodenol, a pair of novel enantiomeric lignans from Liriodendron hybrid

(+)- and (-)-liriodenol, a pair of unprecedented enantiomeric lignans bearing a 1,1-disubstituted olefinic group, were isolated from the barks of Liriodendron hybrid. The structure and relative configurations were determined by comprehensive analysis of MS and NMR spectroscopy. The cytotoxicity of these three lignans ((±)-, (+)-, and (-)-liriodenol) was evaluated in vitro against four selected human tumor cell lines, where (+)-liriodenol showed more significant cytotoxic effects than the (±)- and (-)-liriodenol enantiomers.